Water-soluble films for oral administration of therapeutic agents are well known in the art. It is also known in the art to use such films for administering a breath freshening agent, e.g., menthol. The known films for administering breath freshening agents and/or active pharmaceutical agents are generally comprised of at least one water-soluble polymer suitable for human consumption and at least one compound that enhances the wettability of the water-soluble polymer, typically selected from polyalcohols, surfactants and plasticizers. For example, U.S. Pat. No. 5,948,430 describes a monolayer film which can be adhered to the oral cavity to release a pharmaceutically or cosmetically active ingredient, wherein the film comprises at least one water-soluble polymer; at least one member selected from the group consisting of a polyalcohol, a surfactant and a plasticizer; at least one cosmetic or pharmaceutically active ingredient; and a flavoring agent.
While the disclosed monolayer films dissolve completely without leaving any residue in the presence of sufficient moisture, higher dissolution rates which can be achieved with exposure to lower amounts of moisture are desirable for certain applications. For example, it is highly desirable that a breath freshening film dissolve rapidly in the oral cavity regardless of the moisture level of the mucosal tissue contacting the film. More rapid disintegration of flavored films than is available with known muco-adhesive films may also be desired for use in food items such as poultry, pastries, candies and other confections, etc. In such applications, it may be desirable to impart a localized burst of flavor to the food item using a flavored film that dissolves very rapidly even in the presence of low amounts of moisture.
U.S. Pat. No. 5,700,478 describes a laminated device for controlled release of a substance within a mucosa-lined body cavity including a water-soluble adhesive layer comprised of a water-soluble polymer and a water-soluble plasticizer, and a water-soluble polymer layer. Rather than teaching a rapidly dissolving flavored film, this patent teaches a multiple layer laminate that dissolves relatively slowly for controlled or sustained release of a substance.
U.S. Pat. No. 4,900,552 describes a trilaminate film suitable for prolonged and sustained delivery of an active ingredient in a buccal cavity. The trilaminate includes a hydratable muco-adhesive base layer; a non-adhesive reservoir layer; and a water-impermeable barrier sandwiched between and bonded to the base layer and the reservoir layer. Rather than teaching a rapidly disintegrating film, this patent discloses slowly disintegrating films for prolonged or sustained release of a substance.
U.S. Pat. No. 5,047,244 discloses a therapeutic dosage form comprising an anhydrous but hydratable monolithic polymer matrix that contains amorphous fumed silica as well as a therapeutic agent, and a water-insoluble barrier layer secured to the polymer matrix and defining a non-adhesive face. This patent does not disclose rapidly disintegrating films, but instead contemplates compositions that are capable of providing improved availability of therapeutic agents from a controlled release muco-adhesive carrier system.